1. Field of the Invention
This invention relates generally, to fluid distribution systems and has application, among other uses, to power distribution and control equipment. The invention provides particular benefit in an application to medium and high current circuit interrupters and, more particularly, to compact medium and high current circuit breakers.
2. Background Information
Joule heating along the current path in a circuit breaker is one of the major factors that limits size reduction and load upgrading. Temperature rise at the circuit breaker terminals is regulated according to the cable installation requirements as set in industrial standards. The temperature rise inside medium current circuit breakers is limited by case materials as well as trip units. Due to the nature of medium current circuit breakers, heat transfer between the circuit breakers and their environment is very limited. Typically, heat is transferred out of the circuit breakers by heat conduction through the terminal cables (or bus bars) and natural convection through the circuit breaker cases. This limits the reduction of temperature rise within the cases and, therefore, the current load upgrading ability. Heat transfer is particularly a problem with molded case circuit breakers. While the molded case material is an excellent electrical insulator, it is also an effective thermal insulator.
Accordingly, an improved circuit breaker is desired that provides enhanced heat transfer from its contacts and terminals to the surroundings and environment.